I found a 50s Jupiter 3 on Ebay with M adapter, so have ordered that. I'll check focus on my Sony and on my M3 (a few frames remaining) and hope it's fine.
Thanks to all for the advice, it is much appreciated!
Film amateur with a few rangefinders - Leica III, M2/M3, Werra 3 and Zeiss Super Ikonta 534/16 medium format.
Apart from that have a Rolleiflex 3.5F, the odd Minolta XD7, Hasselblad 500cm, a Topcon Super D and an Intrepid 5x4 large format (not the half of it but I am clearing them out, honest).
I do all my own black and white developing at home.